Many types of products such as ice cream, meat products and prefabricated meals are packed in objects, which have a cavity with an edge. The objects may be trays, bowls or cups. The objects are shaped for packing, transporting and storing in space-saving nested stacks to the site, where the products to be contained are filled into the objects.
The stack of objects is also convenient for loading the objects into a denesting apparatus. The denesting apparatus may be positioned over a conveyor belt, which transports the objects from the nested stack, after having been denested from the stack, to a conveyor and a filling station where the food product or other product is filled into the cavity of the objects. The filled object may subsequently be sealed by application of a lid or other sealing device, and further processed as needed, e.g., heat treated, labelled etc.
To achieve high speed filling and subsequent processing, the objects must be denested reliably and at a high rate of speed from the nested stack in the denesting apparatus.
Satisfactory denesting, however, is difficult to obtain, among others because the objects may be stacked very closely due to the shape of the objects and/or due to the material, which the objects are made of. Shapes of the objects may be rectangular, triangular or other polygonal shape, with more or less rounded corners, or round, oval, or any shape along a circumference of the objects. Materials of the objects may especially be plastic such as polypropylene, PET, APET, CPET, HICEPET, OPS, or metal such as aluminium, or fibrous products such as cardboard, paper and wooden veneer, or any other material, which may be manufactured and used in a configuration of thin sheets, either flat or three-dimensional.
Rapid and precise timing of denesting of an object from a nested stack is difficult to obtain because of frictional forces and vacuum forces holding the object to the stack. Failure of denesting the object from the nested stack of objects on time in a rapid and precise manner may result in intermediate stop of subsequent processing lines.
A denesting apparatus, which provides rapid and precise denesting of objects, is difficult to construct, because the apparatus must support the stack of objects while at the same time releasing an object of the stack. To achieve denesting more rapidly and at a greater precision of only the intended number of objects at a time, conventional denesting apparatuses have utilised various mechanisms for denesting of the objects.
WO 2005/044703, which is hereby incorporated by reference, discloses an apparatus for denesting of stacked objects in a predetermined denesting direction. The denesting apparatus has at least one denesting element for repetitive denesting of at least one object at a time. The denesting element has a first supporting member and a second supporting member for supporting a first object and a second object, respectively, of the stacked objects. The first object is an outermost object and intended for immediate subsequent release in the predetermined denesting direction. The second object is an object neighbouring the first object and situated between the first object and the remaining stack of objects. The denesting element rotates in an initial rotational direction being determined by the at least one initial first object being released from the support of the first supporting member and from the stack of objects, while at the same time an initial second object is still supported by the second supporting member.
GB 935,833 also discloses a dispenser for receptacles. A plurality of finger supporting levers oscillate adjacent the opening through which the receptacles are dropped. The levers extends toward the edge of the opening, and each lever having a pair of vertically and laterally spaced fingers alternately engaging and supporting rims of the receptacles. The vertical spacing of the fingers is substantially equal to the vertical thickness of the rims. One of the fingers is vertically yieldable to compensate for the usual production tolerance variations in the thickness of the rims of the receptacles. The dispenser is not suited for closely stacked receptacles. The dispenser only compensates for the thickness of the rims of the receptacles. The dispenser cannot compensate for a possibly varying distance between the rims of the receptacles.